import com.sun.jdi.PathSearchingVirtualMachine;

import java.util.Enumeration;
import java.util.Scanner;

public class L04 {
    public static void main(String[] args) {
        int []arr={1,2,3,4,5};
        Scanner sc=new Scanner(System.in);
         int num= sc.nextInt();
         int index=-1;
         for (int i=0;i<arr.length;i++){
             if (num==arr[i]){
                 index=i;
                 break;
             }
         }

        System.out.println("您输入的数索引是:"+index);




    }








}
